I struggled with this. I know it's kind of not right and makes me feel a little rapey or whatever, but let me go through a scenario. Say you're making out with a chick assuming you're a straight guy because I'm a straight guy. 99% of women aren't going to tell you that they want to have sex unless you're already past the first time having sex or married.

Anyways you're making out and you want to take it further. Don't ask (because in my experience it has been kind of a mood killer) just go for it. Like stick your hands in her pants or grab her boobs. If she does not want to go that far she will let you know and also you should be able to tell by her reaction. Then most of the time if you get the go ahead for the fingering it's smooth sailing to sex.

It's always been tough for me because in a perfect world I would like to ask before I did or attempted something. Women are different. They communicate with hints and looks and stuff which men are usually horrible at. That's why to me it kind of sort of seems a little rapey attempting to move things along without saying much of anything. Also remember girls are different so some (in my case very few) will be okay with you asking, but most want you move along without saying anything. Just kind of doing what you want. Again she will let you know if you're moving too fast or if she doesn't want to do anything other than kiss/make out. If she doesn't want to go further don't get disappointed or mad or anything. Just move past sex or whatever and continue having a nice time with your lady friend. You might be sexually frustrated if you didn't have sex or whatever. Just go jerk off or something afterwards.